A former Minneapolis police officer is going on trial in the US over the death of George Floyd

Jurors may not wait long to see parts of the bystander video that caught Derek Chauvin’s knee on Mr Floyd’s neck, sparking waves of outrage and activism across the US and beyond.

Prosecutors have not said when they will play the video, but legal experts expect it to be early in the trial – maybe even in the prosecution’s opening statement – as they seek to remind jurors of what is at the heart of their case.

“If you’re a prosecutor you want to start off strong. You want to frame the argument – and nothing frames the argument in this case as much as that video,” said Jeffrey Cramer, a former federal prosecutor and managing director of the Berkeley Research Group in Chicago.

Mr Floyd was declared dead after Chauvin pressed his knee against Mr Floyd’s neck for about nine minutes. He held his position even as Mr Floyd’s “I can’t breathe” cries faded and he went limp as he was handcuffed and lying on his stomach.

Chauvin is charged with unintentional second-degree murder, third-degree murder and manslaughter.

Almost all of the jurors selected during more than two weeks of questioning said they had seen at least parts of the video, and several acknowledged it gave them at least a somewhat negative view of Chauvin. But they said they could set that aside.

The trial is expected to last about four weeks at the courthouse in downtown Minneapolis, which has been fortified with concrete barriers, fencing, and barbed wire. City and state leaders are determined to prevent a repeat of damaging riots that followed Mr Floyd’s death, and National Guard troops have already been mobilised.

The key questions at the trial will be whether Chauvin caused Mr Floyd’s death and whether his actions were reasonable.

For the unintentional second-degree murder charge, prosecutors have to prove Chauvin’s conduct was a “substantial causal factor” in Mr Floyd’s death, and that Chauvin was committing felony assault at the time.

For third-degree murder, they must prove that Chauvin’s actions caused Mr Floyd’s death, and were reckless and without regard for human life. The manslaughter charge requires proof that Chauvin caused Mr Floyd’s death through negligence that created an unreasonable risk.

After jury instructions, prosecutors will begin with their opening statement, providing a road map of their case and telling jurors what they can expect to see at the trial, said Mike Brandt, a local defence lawyer who is watching the case closely. They will outline what is to come, highlighting key witnesses.

Chauvin’s defence lawyer, Eric Nelson, will probably use his opening statement to push back on what prosecutors say, and tell jurors that medical testimony and use of force experts will show a different view.

Fifteen jurors will appear in court on Monday when the case starts, but Hennepin County Judge Peter Cahill said the 15th was chosen simply to ensure that 14 would be in place once the trial begins. He is expected to dismiss that person immediately.

Two of the remaining 14 will be alternates, but the court has not made clear which ones.

Jury selection took more than two weeks, as jurors were questioned individually about their views on police, racial justice issues and pre-trial publicity in the case.